KR20140024381A - Method and apparatus for small cell discovery in heterogeneous networks - Google Patents

Abstract

A method for acquiring and applying offload area information for offloading a wireless transmit / receive unit (WTRU) to a small cell at a different frequency layer is disclosed. The WTRU may receive offload region information of the region entering the region or macro cell and in which the small cell in the vicinity of the macro cell is located. The offload region information includes the global positioning system (GPS) coordinates, the radius the region extends with respect to the GPS coordinates, the list of position reference signals (PRS), the list of cell identities or cell identities, the frequency at which the small cell is located, and the corresponding cell. Radio access technology (RAT). Offload information may be received in a system information block (SIB), dedicated signaling, or any other wireless signal.

Description

METHOD AND APPARATUS FOR SMALL CELL DISCOVERY IN HETEROGENEOUS NETWORKS}

Cross Reference of Related Application

This application claims U.S. Provisional Application No. 61 / 475,063, filed April 13, 2011, entitled "Method for Small Cell Discovery In Heterogeneous Networks," and the name of the invention. Priority is claimed to U.S. Provisional Patent Application 61 / 480,768, filed April 29, 2011, entitled "Method and Apparatus for Small Cell Discovery In Heterogeneous Networks" All of the applications are incorporated herein by reference.

The autonomous search and proximity indication functions in the idle mode and connected mode, the inbound mobility of the wireless subscriber unit (WTRU) to a closed subscriber group (CSG) or hybrid cell that is a member. to facilitate mobility.

Both functions implicitly exist in the presence of a "fingerprint" that allows the WTRU to infer the potential presence of its member CSG or its hybrid cells, even if these cells operate at frequencies that the WTRU is not measuring. Depends. The fingerprint information may include information and / or measurements used by the WTRU to determine whether a particular cell or group of cells is in proximity. Positioning functionality supported in wireless communication standards such as long term evolution (LTE) provides a means for determining the geographical location and / or speed of a WTRU based on measured radio signals.

A method for acquiring and applying offload area information for offloading a wireless transmit / receive unit (WTRU) to a small cell at a different frequency layer is disclosed. The WTRU may receive offload region information of the region entering the region or macro cell and in which the small cell in the vicinity of the macro cell is located. The offload region information includes the global positioning system (GPS) coordinates, the radius the region extends with respect to the GPS coordinates, the list of position reference signals (PRS), the list of cell identities or cell identities, the frequency at which the small cell is located, and the corresponding cell. Radio access technology (RAT). Offload information may be received in a system information block (SIB), dedicated signaling, or any other wireless signal. The WTRU may perform measurements to determine the location of the WTRU and determine whether it has entered any offload region. Upon determining that the offload region is no longer valid, the WTRU may delete the offload region information.

A more detailed understanding may be made from the following description provided by way of example in conjunction with the accompanying drawings.

FIG. 1A is a system diagram of an exemplary communication system in which one or more disclosed embodiments may be implemented. FIG.
1B is a system diagram of an exemplary wireless transmit / receive unit (WTRU) that may be used in the communication system shown in FIG. 1A.
1C is a system diagram of an example radio access network and an example core network that may be used within the communication system shown in FIG. 1A.
2A-2C are flow diagrams of an example method for small cell discovery in a heterogeneous network.

FIG. 1A is a diagram of an exemplary communication system 100 in which one or more of the disclosed embodiments may be implemented. The communication system 100 may be a multiple access system that provides content to a plurality of wireless users, such as voice, data, video, messaging, broadcast, and the like. Communication system 100 may enable multiple wireless users to access such content through sharing of system resources including wireless bandwidth. For example, communication system 100 may include code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), and the like. One or more channel access methods may be employed.

As shown in FIG. 1A, the communication system 100 includes a wireless transmit / receive unit (WTRU) 102a, 102b, 102c, 102d, a radio access network (RAN) 104, a core network 106, a public switched telephone network. (PSTN) 108, the Internet 110, and other networks 112, although it will be understood that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. . Each WTRU 102a, 102b, 102c, 102d may be any type of device configured to operate and / or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d may be configured to transmit and / or receive wireless signals, and may be user equipment (WTRUs), mobile stations, fixed or mobile subscriber units, pagers, cellular phones, personal digital assistants. (PDA), smartphones, laptops, netbooks, personal computers, wireless sensors, consumer electronic devices, and the like.

The communication system 100 may also include a base station 114a and a base station 114b. Each base station 114a, 114b wirelessly interfaces with at least one of the WTRUs 102a, 102b, 102c, 102d to provide one or more communication networks, such as the core network 106, the Internet 110, and / or the network 112. It may be any type of device configured to facilitate access to the. For example, the base stations 114a and 114b may be base station transceivers (BTSs), Node-Bs, eNode Bs, Home Node Bs, Home eNode Bs, site controllers, access points (APs), wireless routers, and the like. While base stations 114a and 114b are each shown as a single element, it will be appreciated that base stations 114a and 114b may include any number of interconnected base stations and / or network elements.

Base station 114a may be part of RAN 104 that may also include other base stations and / or network elements (not shown), for example, a base station controller (BSC), a radio network controller (RNC), relay nodes, and the like. have. Base station 114a and / or base station 114b may be configured to transmit and / or receive wireless signals within a particular geographic area, which may be referred to as a cell (not shown). The cell may be further divided into cell sectors. For example, a cell associated with base station 114a may be divided into three sectors. Thus, in one embodiment, base station 114a may include three transceivers, one transceiver for each sector of the cell. In another embodiment, base station 114a may employ multiple input multiple output (MIMO) technology, and thus may use multiple transceivers for each sector of a cell.

Base stations 114a and 114b are WTRUs 102a over an air interface 116, which may be a suitable wireless communication link (eg, radio frequency (RF), microwave, infrared (IR), ultraviolet (UV), visible light, etc.). , 102b, 102c, 102d). The air interface 116 may be established using any suitable radio access technology (RAT).

More specifically, as described above, communication system 100 may be a multiple access system and may employ one or more channel access schemes such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. For example, the base station 114a and the WTRUs 102a, 102b, 102c in the RAN 104 may use Universal Mobile Telecommunications System (UMTS) terrestrial radio access to establish an air interface 116 using wideband CDMA (WCDMA). Wireless technology such as (UTRA) may be implemented. WCDMA may include communication protocols such as high speed packet access (HSPA) and / or evolved HSPA (HSPA +). The HSPA may include high speed downlink packet access (HSDPA) and / or high speed uplink packet access (HSUPA).

In another embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may evolve UMTS that may establish the air interface 116 using long term evolution (LTE) and / or LTE-Advanced (LTE-A). Wireless technologies such as terrestrial radio access (E-UTRA) can be implemented.

In another embodiment, the base station 114a and the WTRUs 102a, 102b, 102c are IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, Interim Standard 2000 (IS-). 2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile communication (GSM), Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN) Can be implemented.

Base station 114b of FIG. 1A may be, for example, a wireless router, a Home Node B, a Home eNode B, or an access point, and facilitates wireless connectivity in localized areas such as businesses, homes, vehicles, campuses, and the like. Any suitable RAT can be used for this purpose. In one embodiment, base station 114b and WTRUs 102c and 102d may implement a wireless technology such as IEEE 802.11 to establish a wireless local area network (WLAN). In another embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.15 to establish a wireless personal network (WPAN). In another embodiment, base station 114b and WTRUs 102c and 102d utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, etc.) to establish a picocell or femtocell . As shown in FIG. 1A, base station 114b may have a direct connection to the Internet 110. Thus, base station 114b may not be required to access the Internet 110 through the core network 106.

The RAN 104 may be a core network (which may be any type of network configured to provide voice, data, application, and / or voice over internet protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d). 106). For example, the core network 106 may provide call control, billing services, mobile location based services, prepaid calls, internet connectivity, video distribution, and / or perform high level security functions such as authentication. have. Although FIG. 1A is not shown, it will be appreciated that the RAN 104 and / or the core network 106 may be in direct or indirect communication with another RAN employing the same RAT as the RAN 104 or a different RAT. . For example, in addition to being connected to the RAN 104, which may utilize E-UTRA radio technology, the core network 106 may also communicate with other RANs (not shown) that employ GSM radio technology.

The core network 106 may also function as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110 and / or other network 112. [ The PSTN 108 may include a circuit switched telephone network that provides normal telephone service (POTS). The Internet 110 is an interconnected computer network using conventional communication protocols such as Transmission Control Protocol (TCP), User Datagram Protocol (UDP), and Internet Protocol (IP) within the TCP / IP Internet Protocol Suite; It may include a global system of devices. Network 112 may comprise a wired or wireless communication network owned and / or operated by another service provider. For example, network 112 may include another RAN connected to one or more RANs that may employ the same RAT as RAN 104 or different RATs.

Some or all of the WTRUs 102a, 102b, 102c, 102d in the communication system 100 may include multi-mode capabilities, that is, the WTRUs 102a, 102b, 102c, 102d may have different radios over different radio links. It may include multiple transceivers for communicating with a network. For example, the WTRU 102c shown in FIG. 1A may be configured to communicate with a base station 114a that may employ cellular based wireless technology and a base station 114b that may employ IEEE 802 wireless technology. have.

FIG. 1B is a system diagram of an exemplary WTRU 102. FIG. As shown in FIG. 1B, the WTRU 102 includes a processor 118, a transceiver 120, a transmit / receive element 122, a speaker / microphone 124, a keypad 126, a display / touchpad 128, Non-removable memory 106, removable memory 132, power source 134, global positioning system (GPS) chipset 136, and other peripherals 138. It will be appreciated that the WTRU 102 may include any sub-combination of the above elements while remaining consistent with an embodiment.

Processor 118 is a general purpose processor, special purpose processor, conventional processor, digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors associated with a DSP core, controller, microcontroller, application specific integrated circuit (ASIC) , Field programmable gate array (FPGA) circuitry, any other type of integrated circuit (IC), state machine, or the like. The processor 118 may perform signal coding, data processing, power control, input / output processing, and / or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to a transceiver 120 that may be coupled to the transceiving element 122. Although FIG. 1B shows the processor 118 and the transceiver 120 as separate components, it will be appreciated that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

The transmit / receive element 122 may be configured to transmit signals to or receive signals from the base station (eg, base station 114a) over the air interface 116. For example, in one embodiment, the transceiving element 122 may be an antenna configured to transmit and / or receive an RF signal. In another embodiment, the transceiving element 122 may be an emitter / detector configured to transmit and / or receive an IR, UV or visible light signal, for example. In yet another embodiment, the transmit / receive element 122 may be configured to transmit and receive both RF and light signals. It will be appreciated that the transceiving element 122 may be configured to transmit and / or receive any combination of wireless signals.

In addition, while the transmit / receive element 122 is shown in FIG. 1B as a separate element, the WTRU 102 may include any number of transmit / receive elements 122. More specifically, the WTRU 102 may employ MIMO technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit and receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals via the air interface 116. [

The transceiver 120 may be configured to modulate the signal to be transmitted by the transceiving element 122 and to demodulate the signal received by the transceiving element 122. As mentioned above, the WTRU 102 may have multi-mode capabilities. Thus, the transceiver 120 may include multiple transceivers to enable the WTRU 102 to communicate via multiple RATs, such as, for example, UTRA and IEEE 802.11.

The processor 118 of the WTRU 102 may include a speaker / microphone 124, a keypad 126, and / or a display / touchpad 128 (eg, a liquid crystal display (LCD) display unit or an organic light emitting diode (OLED)). Display unit] and receive user input data from them. Processor 118 may also output user data to speaker / microphone 124, keypad 126, and / or display / touchpad 128. In addition, the processor 118 may access and store data in any type of suitable memory, such as non-removable memory 106 and / or removable memory 132. Nonremovable memory 106 may include random access memory (RAM), read only memory (ROM), hard disk, or any other type of memory storage device. Removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, and the like. In other embodiments, processor 118 may access and store data in memory that is not physically located on WTRU 102, such as a server or home computer (not shown).

The processor 118 may receive power from the power source 134 and may be configured to distribute and / or control power to other components within the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. For example, the power supply 134 may include one or more dry cell batteries (eg, nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion), or the like. ], A solar cell, a fuel cell, and the like.

The processor 118 may also be coupled to a GPS chipset 136 that may be configured to provide location information (e.g., longitude and latitude) with respect to the current location of the WTRU 102. In addition to or instead of information from the GPS chipset 136, the WTRU 102 may receive location information via the air interface 116 from a base station (eg, base stations 114a and 114b) and And / or determine its location based on the timing of signals received from two or more nearby base stations. It will be appreciated that the WTRU 102 may obtain location information via any suitable location-determination method while remaining consistent with the embodiment.

모듈, 주파수 변조(FM) 라디오 유닛, 디지털 뮤직 플레이어, 미디어 플레이어, 비디오 게임 플레이어 모듈, 인터넷 브라우저 등을 포함할 수 있다.Processor 118 may be further coupled to other peripherals 138 that may include one or more software and / or hardware modules that provide additional features, functionality, and / or wired or wireless connectivity. For example, the peripheral device 138 may include an accelerometer, an electronic compass (e-compass), a satellite transceiver, a digital camera (for photos or videos), a universal serial bus (USB) port, a vibration device, a television transceiver, a handsfree headset, Bluetooth

Modules, frequency modulated (FM) radio units, digital music players, media players, video game player modules, Internet browsers, and the like.

1C is a system diagram of a RAN 104 and a core network 106 in accordance with an embodiment. As described above, the RAN 104 may employ E-UTRA radio technology to communicate with the WTRUs 102a, 102b, and 102c through the air interface 116. [ The RAN 104 may also communicate with the core network 106.

The RAN 104 may include eNode-Bs 160a, 160b, 160c, although it may be understood that the RAN 104 may include any number of eNode-Bs while remaining consistent with an embodiment. There will be. The eNode-Bs 160a, 160b, 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, eNode-B 160a, 160b, 160c may implement MIMO technology. Thus, eNode-B 160a may use multiple antennas to, for example, transmit wireless signals to and receive wireless signals from WTRU 102a.

Each eNode-B may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in uplink and / or downlink, and the like. As shown in FIG. 1C, the eNode-Bs may communicate with each other via an X2 interface.

The core network 106 shown in FIG. 1C may include a mobility management gateway (MME) 162, a serving gateway 164, and a packet data network (PDN) gateway 166. While each of these elements is shown as part of the core network 106, it will be understood that any one of these elements may be owned and / or operated by an entity other than the core network operator.

The MME 142 may be connected to each eNode-B 162a, 162b, 162c in the RAN 104 via the S1 interface and may function as a control node. For example, MME 162 may be responsible for authenticating users of WTRUs 102a, 102b, 102c, enabling / disabling bearers, selecting specific serving gateways during initial connection of WTRUs 102a, 102b, 102c, and so forth. Can be. The MME 162 may provide a control plane function for switching between the RAN 104 employing other radio technologies such as GSM or WCDMA and another RAN (not shown).

The serving gateway 164 may be connected to each eNode B in the RAN 104 via the S1 interface. Serving gateway 164 is generally capable of routing and forwarding user data packets to / from WTRUs 102a, 102b, and 102c. The serving gateway 144 also anchors the user plane during inter-eNode B handovers, triggers paging when downlink data is available for the WTRUs 102a, 102b, 102c, and determines the availability of the WTRUs 102a, 102b, 102c. Other functions such as managing and storing contexts can be performed.

The serving gateway 164 may also be connected to a PDN gateway 166 that may provide the WTRUs 102a, 102b, 102c with access to a packet switched network, such as the Internet 110, to allow the WTRUs 102a, 102b, 102c) and facilitates communication between the IP-enabled device.

The core network 106 may facilitate communication with other networks. For example, the core network 106 can provide the WTRUs 102a, 102b, 102c with access to a circuit switched network, such as the PSTN 108, to provide traditional land line communication with the WTRUs 102a, 102b, 102c. Facilitate communication between devices. For example, the core network 106 may include or communicate with an IP gateway (eg, an IP Multimedia Subsystem (IMS) server) that serves as an interface between the core network 106 and the PSTN 108. In addition, the core network 106 may provide the WTRUs 102a, 102b, 102c with access to the network 112, which may include other wired or wireless networks that are owned and / or operated by other service providers. .

LTE Positioning Protocol (LPP) has evolved a Serving Mobility Location Server (E-SMLC) or a Location Server, such as a Secure User Plane (SUPL) Location Platform (SLP) for Location, and a SUPL-enabled Terminal (SET) or Used point-to-point between target devices, such as WTRUs, to locate the target device using location-related measurements obtained by one or more reference sources. An LPP session is used between the location server and the target device to obtain location related measurements or location estimates or to transmit auxiliary data. LPP session may be initiated by the WTRU, eNB or E-SMLC. In the case of an eNB initiated location determination, the eNB then sends a location service request to the MME forwarding it to the E-SMLC. The E-SMLC may include sending assistance data to the target WTRU to assist with WTRU based and / or WTRU assisted positioning and / or process a location service request that may include positioning of the target WTRU. The E-SMLC then returns to the MME the results of the location service (eg, location estimation for the WTRU and / or indication of any assistance data sent to the WTRU). In the case of location services requested by an entity other than an MME (such as an eNB), the MME returns a location service result to the eNB.

Positioning reference signal (PRS) is added to the downlink physical transmission to assist in WTRU based observed time difference of arrival (OTDOA) position estimation. The PRS is transmitted in a resource block in the configured downlink subframe, and resources are mapped by being offset by a physical cell identity (PCI) of the cell.

System capacity can be maximized by offloading traffic from the macro cell to the small cell. A “small cell” may refer to a cell, such as, but not limited to, an open cell or a hybrid cell whose coverage area is generally limited in size and accessed by the WTRU.

When the macro layer is deployed on a different frequency than the small cell layer, the WTRU operating on the macro layer in a battery efficient manner (in children or connected mode) can take inter-frequency measurements when the quality or signal strength of the serving cell is low. have. Thus, offloading to a small cell deployed in a region where the serving cell is sufficiently strong may not occur. One exception may be when the small cell is a CSG or hybrid cell of which the WTRU is a member, in which case the WTRU may use autonomous discovery to detect a request for inter-frequency measurements and send a proximity indication to the network when in connected mode. .

A method of allowing offloading to small cells in different frequency layers without compromising the battery consumption of the WTRU is described in more detail below. The method described herein may also be applicable to small cells at the same frequency or to small cells at different radio access technologies (RATs). The small cell can be, for example, an LTE, UMTS, GERAN or 802.11 cell.

Disclosed herein is a method for enabling acquisition and storage of information for detection of small cells.

A method is described that enables a WTRU to obtain and store information at at least one location of at least one small cell in which the WTRU may be offloaded. Such information about a specific location may be referred to as "offload area information" in the following example.

The offload area information is at least one offload area, GPS, which may include at least one small cell, which may be a radius and an area provided by a center point (e.g., defined by GPS coordinates). This at least one macro cell (along with a set of coordinates, an area formed by a plurality of GPS coordinates (e.g., the X coordinate defines a limit of the area where the small cell is available), the coverage area of at least one macro cell ( The identity of PCI, CGI), one or a combination of at least two of the above, but is not limited thereto. Another example of offload area information is a reference any reference signal (eg, location reference symbol (PRS), CSI-RS, CRS), list of PCI or PCI, list of cell identity or cell identity, cell location Frequency of the WTRU as determined by a predetermined frequency, the RAT of the corresponding cell, or the area under a particular macro cell defined by any of the aforementioned location information, any of the well known location methods described above. Can be.

The WTRU then initiates idle mode, inter-frequency or inter-RAT measurements, as described in more detail herein below, to enable potential cell reselection to small cells included in the offload region, or connect. It is possible to send an offload indication in mode so that the network provides the appropriate updated configuration at the right time as appropriate to enable potential handover to the small cells contained within the offload region, for example frequency Stored offload region information for at least one location may be used to perform at least one of inter- or inter-RAT or intra-frequency measurement configuration, DRX configuration, or mobility state estimation configuration.

Disclosed herein is a method of transmission of an offload indication to a RAN. In this embodiment, the WTRU is responsible for entering or leaving the vicinity of one or multiple neighboring cells (eg, picocells operating on different frequencies or RATs) and for potential handover to one of these cells ( Send an “offload indication” to the RAN to indicate that it may be configured with inter-frequency or inter-RAT measurements (for offload purposes) or that measurement configurations on different frequencies or RATs may be removed when leaving the indication. Can be.

WTRUs moving beyond a certain speed through the macro layer may not be a good candidate for offloading to the small cell layer. In this case, the network may use the WTRU rate information to assist in determining whether offload is required.

The "offload indication" message may include any of the following information elements. The IE includes, but is not limited to, a new RRC message, ie, “offload indication”, to indicate that the WTRU is a candidate for traffic offload. An existing “Proximity Indication” RRC message may be used to indicate to the RAN that the WTRU is in the vicinity of the CSG cell it potentially accesses. Existing "proximity indication" RRC messages may be modified to include additional information elements that may be used for offload purposes and to indicate that the reason for sending the indication is for offload purposes. Alternatively, existing RRC message reporting messages may be modified to include additional information elements that may be used for offloading purposes. In another embodiment, a new measurement type “offload indication” may be introduced and reported in the RRC measurement report. In addition, the “Proximity Indication” measurement type may be extended to provide offload information and to explicitly indicate to the network that proximity is due to offloading rather than CSG or for both.

The offload indication message may be offloaded by any of the following information elements: an indication of whether the WTRU enters or leaves the offload area, the WTRU may be indicated by an identifier or an index, or an offload area tag. Offload area, frequency at which the WTRU can be offloaded, cell ID of the potential target cell (s) at which the WTRU can be offloaded, PCI at potential target cell (s) at which the WTRU can be offloaded, WTRU May also include at least one of a radio access technology that may be offloaded, an area in which the WTRU is located (eg, GPS coordinate (s) or other location based information may be provided), and WTRU mobility status information. have. In addition, the radio access technology of the cell may be indicated (eg, LTE, UMTS, 802.11, etc.). For an 802.11 cell, the WTRU may further provide additional information such as channel, SSID, MAC address, and the like.

The transmission of the offload indication may be triggered when the WTRU determines that it has entered the offload area. The determination that the WTRU has entered the offload region may be made by comparing its location to stored offload region information or offload region information provided by the RAN.

The transmission of the offload indication may be triggered when the WTRU determines that it has left the offload area. The determination that the WTRU has left the offload area may be made by comparing its location to stored offload area information or offload area information provided by the RAN.

For the conditions described above, the WTRUs are not limited to these, but include GPS coordinate estimation, LTE positioning methods (e.g., use of PRS transmitted from multiple transmission points to estimate its location) or any other location. Any well-known location determination technique, such as a verification method, can be used to determine its current location.

Moreover, it is understood that the UE can determine its current location based on the detected neighboring cell or neighboring cell with channel measurements exceeding a threshold.

The conditions described above for triggering the transmission of the offload indication may be further refined based on any of the conditions described herein.

For example, triggering may further consider the mobility state of the UE. For example, the WTRU sends an offload indication if it determines that it is in a "low mobility state" and / or "medium mobility state". More specifically, the offload indication is triggered when the UE determines the entry state and when the UE is considered to be in a "low mobility" state. Otherwise, if the UE is not in the low mobility state, it does not send an offload indication. Determination of the UE mobility state may be made based on using any well-known positioning technique such as, but not limited to, GPS information, LTE positioning method, or any other positioning method. For example, the WTRU may determine its mobility state based on the speed calculated through GPS measurements or through a rate of change of GPS coordinates. The WTRU speed may be compared with a predetermined threshold to determine whether the WTRU is in a low mobility state or a high mobility state. The "low mobility state" may also be determined based on the rate of change of the DL reference signal transmitted by one or multiple transmission points. The "low mobility state" may also be based on the rate of change of the best cell event or the handover rate. The “low mobility state” may also be based on the rate of change in WTRU location calculated using the LTE location method (eg, using a location reference symbol to determine the WTRU location). The rate of change in WTRU location may be compared with a predetermined threshold to determine whether the WTRU is in a low mobility state or a high mobility state.

The mobility state of the UE may depend on existing mobility state estimation procedures. The UE may then use the mobility state in combination with the determination of entering or leaving the offload to trigger the offload indication. In one example, if the WTRU is in an offload region and the indication is pretriggered and the mobility state is changed to "high mobility state", the WTRU may trigger the offload instruction, which may leave the region or mobility Provides information about what has changed state.

Triggering may also take into account traffic activity, causing the WTRU to send an offload indication based on the traffic activity, ie the traffic heavy WTRU may be a candidate for offloading to another cell. For example, the determination that the WTRU is a high traffic activity may be based on DL 占 ° and / or UL data rate transmissions averaged over a specific time period. Triggering may also take into account network indications and configurations, such as sending offload instructions if the WTRU is allowed to be done by the network when indicated (or configured) by the RRC configuration or in the system information. Triggering also restricts the WTRU from triggering a new offload indication message unless the time limit from the last "offload indication" has elapsed (e.g., the WTRU is restricted from sending a new offload indication during the configured time period. ) May be limited by a limit timer. The offload indication may be triggered once (e.g., the UE is in the offload area) and if a handover to a new cell occurs (e.g., upon handover to a new cell), the new offload indication is Triggered to notify new macro cells of the offload). Alternatively, the WTRU may not need to resend the indication, but the source eNB forwards the information to the target eNB in the handover preparation (request) phase.

Control of inter-frequency measurements in idle mode is disclosed herein. The WTRU may start or stop inter-frequency or inter-RAT measurements in idle mode based on the stored offload region information, according to at least one of the following methods. The WTRU may initiate inter-frequency or inter-RAT measurements on at least one frequency or RAT if at least the WTRU determines that the cell has entered an offload region in which the cell is deployed at this frequency or RAT. Determination of the WTRU entering the offload area may be made by comparing its location to the offload area information or stored offload area information provided by the RAN. The WTRU is on at least one frequency or RAT if the WTRU determines that it has left the offload region where the cell is deployed on this frequency or RAT (and the cell is not in any other offload region that is deployed on this frequency or RAT). Inter-frequency or inter-RAT measurements can be stopped. The determination that the WTRU has left the offload area may be made by comparing its location to stored offload area information or offload area information provided by the RAN. In one example, when the WTRU determines that it is at least in the vicinity of the small or offload cell, the WTRU may consider the frequency of the small cell as the highest priority frequency for cell reselection purposes.

The conditions described above for initiating or stopping inter-frequency or inter-RAT measurements can be further refined based on any of the examples provided herein. The WTRU may initiate an inter-frequency or inter-RAT measurement if it determines that it is in a particular mobility state, such as a "low mobility state" or a "medium mobility state." The determination of the "low mobility state" may be based on the GPS information. For example, the WTRU may determine its mobility state based on the speed calculated through GPS measurements or through the rate of change of GPS coordinates. The WTRU speed may be compared with a predetermined threshold to determine whether the WTRU is in a low mobility state or a high mobility state. Alternatively, the determination of the "low mobility state" may be based on the rate of change of the DL reference signal transmitted by one or multiple transmission points. Alternatively, the determination of the "low mobility state" may be based on the rate of change of the best cell event or the handover rate. Alternatively, the determination of the "low mobility state" may be based on the rate of change in the WTRU location calculated using the LTE location method (eg, using the PRS reference symbol to determine the WTRU location). . The rate of change in WTRU location may be compared with a predetermined threshold to determine whether the WTRU is in a low mobility state or a high mobility state.

The mobility state of the UE may depend on existing mobility state estimation procedures. The UE may then use the mobility state in combination with the determination of entering or leaving the offload region to determine to start an inter-frequency or inter-RAT measurement. In one example, if the WTRU is in the offload region and the indication is pretriggered and the mobility state is changed to "high mobility state", the WTRU may trigger the offload instruction, indicating that it is leaving the region or Provides information that the mobility state has changed.

Even if the WTRU does not leave the offload area, it may stop inter-frequency or inter-RAT measurements if it determines that it is no longer in a particular mobility state, such as a "low mobility state" or a "medium mobility state".

The WTRU may stop performing measurements if the WTRU performs inter-frequency or inter-RAT measurements during the configured time period or does not detect any valid candidate cells in the vicinity. This may also indicate that the offload area information stored in the WTRU is no longer valid. Preferably, in this determination, the WTRU may remove the stored information.

Management of offload area information is described herein. The method may be used to determine if the WTRU has the necessary offload area information stored for potential transmission of the offload indication message (in connected mode) or for initiation of inter-frequency measurements (in idle mode).

The WTRU may autonomously store offload region information based on previously detected small cells and, for example, build fingerprints of databases or small cells, their frequencies, locations, and the like.

Alternatively, the network may explicitly provide WTRU offload area information to assist the UE in discovering and reporting the vicinity of the small cell. Alternatively, the WTRU may build offload area information using a combination of autonomous storage of information and those based on information explicitly provided by the network.

In one method, the WTRU may determine that it lacks valid offload region information for at least one small cell or that it desires to request offload region information or initiates acquisition of offload region information. have. This determination is made using the received information for small cells (PCI, CGI, CSG ID, operating frequency) for which valid offload area information needs to be available, and such information is not available for at least one small cell. It can be enabled by detecting something not. The WTRU is configured to receive at least one small cell by receiving information about the macro cell (such as PCI, operating frequency) or by accessing the macro cell where the WTRU connected or camped to this macro cell needs to have valid offload area information. It may also be determined that there is a lack of valid offload region information for the system. The WTRU receives a value identifying the offload area information ("offload area tag") at the network level and determines if the offload area information associated with this identifier is stored so that this is a valid offload for at least one small cell. It can also be determined that there is no area information. The WTRU receives a value that identifies offload region information associated with the macro cell (“offload region tag”) and compares this value to an identifier that was stored by the WTRU when offload region information was requested for this macro cell. It can also be determined that this lacks valid offload area information for at least one small cell.

The WTRU may determine that it lacks valid offload area information the first time it visits the area, and stores nothing for this area or for the connected cell (eg, based on PCI, cell ID).

For example, an offload region tag can be associated with a particular macro cell and a set of small cells in its vicinity. Each time a set of small cells is modified or whenever offload area information associated with these cells is modified (due to a change in deployment), the network may change the offload area tag to a different value. This allows the WTRU to detect that the stored offload area information for the small cell in the vicinity of this macro cell is invalid if the stored offload area tag is different from the offload area tag provided by the network.

The WTRU may determine offload region information for at least one small cell by determining that it lacks valid offload region information or that the speed of the WTRU is lower than a threshold that may be predefined or provided by a higher layer. It may also determine that it may request or want to acquire. The WTRU may request or obtain offload region information for at least one small cell by determining that it lacks valid offload region information or that a certain minimum time has elapsed since the last handover or cell reselection. It may also be determined as desired, where the minimum time may be predefined or provided by a higher layer. The WTRU may also determine that it wants to request or obtain offload region information for at least one small cell by determining that it lacks valid offload region information or that the WTRU is in a "low mobility" state. .

WTRUs moving beyond a certain speed through the macro layer may not be good candidates for offloading to the small cell layer. In this case, the WTRU may determine that no offload area information is requested.

The WTRU may also determine that there is no valid offload area information for at least one small cell by determining that a particular minimum time has elapsed since the last handover or cell reselection, where the minimum time is predefined or It may be provided by a higher layer. This is to prevent premature offloading to the small cell layer as the WTRU moves quickly. Alternatively, the WTRU may lack the effective offload region information or by comparing the time when offload region information for at least one small cell was updated and this time is the time before the time limit determined by the maximum threshold. It may also be determined that it may be desired to request or obtain offload region information or to update (eg, modify, remove, add) offload region information for at least one small cell by determining that. The maximum threshold (or time or period limit) may be predefined or provided by the network. The WTRU may also determine that the offload region information is invalid if the time since the offload region was obtained exceeds the time limit.

The WTRU may determine that existing offload region information is not valid upon handover to a new macro cell. For example, if a handover to a macro cell occurs, the WTRU may determine that the stored offload area information is no longer valid and can be removed. If new offload region information is provided in the handover message or in the SIB of the new cell, the WTRU may store the new information. Alternatively, upon handover, the WTRU may maintain previous offload area information (until it is determined to be invalid based on the other criteria). When new offload region information is received from a new macro cell or from an RRC reconfiguration message, the WTRU may replace the stored offload region information or alternatively store the new offload region information in addition to the prestored one.

Upon determining that the offload area information is invalid, present or not obtained, the information is either received by an information element (IE) in a reconfiguration message (such as a handover procedure to a macro cell) or a new macro cell reselected by the WTRU. Can be obtained from SIB. For example, there may be a Boolean IE that indicates whether a small cell exists in the vicinity of the target macro cell for which offload area information needs to be stored. In another example, an IE containing a list of small cells in the vicinity of the target macro cell for which offload region information needs to be stored or an IE containing offload region information for the current UE location (eg, current connection Macro cells) may be present.

Upon determining that offload region information is invalid, the information can be obtained by receiving an information element from a system information broadcast from the macro cell. For example, there may be a Boolean IE in the system information block that indicates whether a small cell exists in the vicinity of the macro cell where the offload area information needs to be stored.

The WTRU may determine that at least one of the following events occurs, i.e. after cell reselection or handover to a cell (or macro cell), upon expiration of a timer started at cell reselection or handover to a cell, where the value of the timer is May be pre-defined or provided by a higher layer; upon explicit indication or request or configuration by the network, a period may be predefined here, or provided by a higher layer, the WTRU At the expiration of the timer started at the last time of verifying whether the information is valid offload region information, it is possible to verify whether there is no valid offload region information.

The WTRU may always search and take measurements to determine proximity to the small cell based on offload region information or fingerprint information on the small cell. The WTRU may autonomously determine when it starts to take measurements depending on the cell to which it is connected. For example, offload region information may be associated with a cell within the used frequency. The cell may be a cell (serving cell or camped cell) to which the UE is connected and may be associated with a PCI, list of neighboring PCIs, or CGI (cell identity) of the serving cell. When the UE determines that PCI or CGI corresponds to a cell stored in its offload region, it may initiate a measurement procedure to detect in the vicinity of the small cell region (eg, GPS, PRS, other positioning method). , Or measurements on other frequencies).

Upon determining that there is a lack of valid offload region information, the WTRU may initiate a procedure to obtain offload region information.

A method for obtaining offload area information is described below. In idle mode, the WTRU may initiate inter-frequency measurements even when the signal strength and / or quality of the serving cell is higher than the thresholds SintrasearchP and SintrasearchQ. Alternatively, the WTRU may perform inter-frequency measurements when the signal strength and / or quality of the serving cell is below a new threshold applicable in the absence of valid fingerprint information.

The WTRU may direct the network the capability and support of offload area and small cell detection.

The WTRU may initiate a procedure to obtain offload region information by sending an indication to the network informing that the offload region information is missing. Upon receipt of this indication, the network may configure the WTRU to perform inter-frequency measurements (in connected mode) or initiate a procedure to provide offload area information to the WTRU. The indication may be provided as part of a new or existing RRC procedure or by MAC signaling (MAC control element). The indication may include a proximity indication or an offload indication. The indication is the reason for sending information about the cell that lacks associated offload area information such as PCI, PCI range, CSG, CSG ID, cell identity (CGI), frequency, RAT, etc., WTRU May include at least one of a cause indication for indicating that the effective offload area information is lacking.

The WTRU may determine that at least one of the following events occurs, i.e. after cell reselection or handover to a cell (or macro cell), upon expiration of a timer started at cell reselection or handover to a cell, where the value of the timer is Pre-defined or provided by a higher layer, upon explicit indication or request by the network, periodically, where the period may be pre-defined or provided by a higher layer, the WTRU sends an indication to the network At the expiration of the timer started at the last time, or after acquisition of offload area information (eg, using its own measurements), an indication may also be sent to the network informing it of storing offload area information. have.

The indication sent to the network may be provided as part of a new or existing RRC procedure, or by MAC signaling (MAC control element). The indication may include a proximity indication or an offload indication. The indication may include at least one of any information included as part of the offload area information as described in the previous paragraph, or a cause indication for indicating that the indication provides offload area information.

In order to avoid storing offload area information indefinitely and to avoid having outdated offload area information, the WTRU may use the following triggers, that is, a validity timer has expired for some offload area information. The WTRU is moving away from the cell (eg, due to cell reselection or due to handover), the WTRU is moving to idle mode, and the WTRU performs an inter-frequency or inter-RAT handover. The WTRU is moving outside the home PLMN, the WTRU changes the PLMN, the WTRU enters the roaming PLMN or the visiting PLMN (alternatively, the WTRU does not delete the offload area information of the home PLMN, Do not store any information for the PLMN), the WTRU is explicitly mentioned by the network to delete offload area information, the WTRU changes the RRC state, Alternatively, the WTRU may erase and delete the stored information according to at least one of obtaining new offload area information (eg, it deletes previously stored information and stores a new one).

Acquisition of offload area information is described herein. The WTRU may apply the methods or procedures, for example, if the offload area information determines that it is not available or valid according to one of the methods described herein, for example.

In one embodiment, the WTRU may obtain and store offload area information based on its own measurements. The measurement may include any possible information that includes or is part of the offline area information. Acquisition and storage of offline area information is subject to the following conditions: the WTRU camps or is connected to a cell associated with this offload area information, the cell is an open cell, the cell is a hybrid cell, the WTRU is associated with a valid offload Determining that there is no area information or that the time elapsed since the last time that the WTRU acquired the offload information is greater than the threshold value, and the WTRU may apply to this offload area information via, for example, a synchronization signal (PSS / SSS). Detecting the presence of the cell with which it is associated, wherein an inter-frequency or inter-RAT measurement is configured in connected mode, the WTRU determines that it does not have valid offload area information associated with the cell, the WTRU for example GPS or location Configured to perform positioning measurements based on the acknowledgment reference signal, or allow the WTRU to acquire and store offload area information associated with this cell. There are at least one or a combination can be carried out when satisfying one of receiving an indication from the network to. In the last case, the indication may be provided in any RRC message such as a handover command or a reset command in which the target cell is a small cell or in the system information of the small cell. The indication may include information about a cell from which associated offload area information such as PCI, range of PCI, CSG, CSG ID, cell identity (CGI), frequency, RAT, etc. is obtained.

In another embodiment, the WTRU may be provided with explicit offload area information by the network. The information provided by the network may include any information that may be part of offload area information (eg, GPS coordinates, radius, cell identity, etc.) as described in the previous paragraph. The network may be responsible for the following events: WTRU enters macro cell coverage (e.g., handover occurs), WTRU performs cell reselection to macro cell (e.g. Information may be broadcast), the network determines that no valid offloaded area information is available within the WTRU, and at any time during operation, upon explicit request by the WTRU to provide such information. Alternatively, this information may be provided in combination. More specifically, such offload region information may be obtained in the following manner, that is, RRC connection reconfiguration (with or without mobilityControlInfo) received at handover to a macro cell whose coverage region includes offload region (s), RRC. Insert into an existing RRC message, such as at least one of a connection reset, an RRC connection setup, an RRC disconnection (to provide fingerprint information in idle mode), system information (eg, for idle mode), a new RRC message May be provided as part of a new information element or as part of a new RRC procedure.

The new RRC procedure may be initiated by the WTRU upon determining that it lacks valid offload area information for at least one cell, as described in the previous section. This can avoid unnecessary signaling if the WTRU has valid information in advance. To enable initiation of this procedure by the WTRU in idle mode, the WTRU may initiate an RRC connection request with a new cause value.

The cell involved in the RRC signaling may be any cell, such as a macro cell whose coverage area includes at least one offload area or a cell associated with the offload area.

Exemplary implementations of the methods described herein are illustrated below. More specifically, this example illustrates how the WTRU is explicitly provided with offload region information.

In this example, the WTRU enters an area or macro cell. At handover, the macro cell provides the WTRU with offload region information of the region where the small cell in the vicinity of the macro cell is located. For example, the offload region information may include GPS coordinates and a radius that the region extends relative to the GPS coordinates. Alternatively, multiple GPS locations (e.g., four) are provided to the WTRU, and the offloading area may correspond to all points located within these coordinates. Another example of location information that may be provided to the WTRU may be the PRS of multiple cells. If more than one offloading area information is available under the coverage of the macro cell, the WTRU may be provided with more than one offloading area location information. The WTRU may also have the frequency or RAT of the cell (s) in the signaled region. The WTRU may obtain this information from the SIB or the macro cell may be provided to the WTRU via dedicated signaling.

Upon obtaining and / or storing this information, the WTRU may determine its location and perform measurements to determine whether it has entered any one of the stored offload areas. The WTRU may use the reception of this offloading area information to trigger and activate the measurement procedure. For example, this may include activating GPS or initiating a PRS measurement if not already activated. Alternatively, a message may be sent indicating that the UE should start a measurement procedure to detect proximity / nearness of the offload area (if already present in the WTRU). This message may not include offload information. These measurements can be performed at the current operating frequency. When the WTRU determines that it has entered an offloading area configured according to any of the coordinates or location information, this may trigger an offload indication. The indication may notify the network that the WTRU has entered the area. As an example, the WTRU may provide its location to the network so that the network can determine which offload region is in the vicinity of the WTRU. As another example, the WTRU only reports the frequency at which the offloading cell can be located. If more than one offload information is provided to the WTRU, the WTRU may also report an index indicating in which area it entered the configured or stored location area.

The WTRU may then be configured to start taking inter-frequency measurements or inter-RAT measurements. The decision for inter-frequency measurement may be network based, or alternatively in an idle mode WTRU, the WTRU may autonomously decide to start taking measurements when it determines to enter in the vicinity of this area.

In one example, upon leaving the macro cell, the WTRU may delete this location information and may initiate the same procedure if new coordinates are provided to the WTRU.

A method of reporting location information to a network is described herein. Another way of allowing WTRU mobility from the macro cell to the small cell is to use location information from the WTRU to determine if it can be in the vicinity of the small cell. This method can assist in cases where self-organized small cell deployment and small cells are turned on and off to dramatically conserve energy. In this way, the WTRU may report its location to the network. Position and measurement can be taken at the frequency used. Using this information, the network can determine when and whether to configure inter-frequency measurements for the WTRU. Once the location information is available, the serving eNB can use it to calculate the absolute distance between the WTRU and the small cell eNB close to it, and once the WTRU is determined to be within proximity, appropriate measurements can be initiated. The calculation of the absolute distance is possible when the serving eNB also has the location information of the small cell eNB available. This information can be assumed to be available to the network when the small cell is deployed in the network or in the case of autonomous HeNB deployment, and the HeNB sends their location information to the network to ensure that the emergency call request is maintained.

A WTRU based positioning method is described herein. In the case of WTRU-based positioning, the result of the measurement is reported using one or more of the following means, i.e. by inserting information into the measurement report triggered by any event as part of an LPP (LTE Positioning Protocol) message. Or alternatively may be reported by including location information in the offload indication or in the extended proximity report. In the case of WTRU-based location determination, an LPP session may need to be initiated to report information to the eNB and the E-SMLC. Similar methods may also be applicable for GPS measurements.

In one embodiment, the LPP session is initiated by the eNB for a candidate WTRU that may be likely to receive location information. The determination of candidate WTRUs performed by the eNB may be based on various factors including measurements, detected serving and neighbor cell-ids, OA & M (operation maintenance maintenance) information, deployment vector maps, and the like.

In another embodiment, the WTRU may be configured to start / stop adding location information to the measurement report when a configured threshold added to the measConfig message is reached. The request may be in the form of a one hour request or in the form of a period measurement request for offloading information.

i, t_i(위치의 x, y 및 z 성분 및 송신된 시간)에 의해 지정된 위치 내의 X 미터의 반경 내에 있는 것을 검출할 때 새로운 이벤트가 네트워크에 위치 확인 보고를 송신하는 것을 개시하도록 생성될 수 있다. 이 이벤트는 측정/LPP 메시지 보고를 트리거링하기 위해 새로운 측정 이벤트 또는 LPP 이벤트일 수 있다.In another embodiment, the WTRU may be configured to report location information when the WTRU detects its movement within proximity of a preconfigured location. For example, the WTRU says that this is the coordinate x _i , y _i

A new event can be generated to initiate sending a location report to the network upon detecting that it is within the radius of the X meter within the location specified by i, t _i (the x, y and z components of the location and the time transmitted). have. This event may be a new measurement event or LPP event to trigger measurement / LPP message reporting.

In another alternative, the small cell eNB (i.e. picocell eNB or HeNB) operating at a different frequency may transmit a reference signal or message at the same frequency as the serving eNB, thus within the serving eNB and the listening radius of the small cell. The WTRU operating within may use an autonomous procedure to detect this. This may be reported to the network using an extension of an existing measurement event and may be defined to initiate an extended proximity indication or new offload indication report or a report in which a new LPP or measurement configuration event is sent to the network. For example, in one alternative, the small cell eNB may transmit a reference signal (eg, of PRS, CRS, CSI-RS) with a certain planned periodicity or at a neighboring frequency (configured or detected). And there is therefore no conflict between neighboring eNBs. The WTRU may be configured to detect all PRS symbols he hears from subframe 0 to subframe T, where T is a superset of the PRS periodicity of all neighbors within a particular region. In one example, the network may configure the WTRU with information and resources over which the reference signal is sent. The WTRU then monitors the same frequency as the frequency used for this reference signal or PRS, and when the WTRU detects reference signals or when the quality of one or a subset of these reference signals exceeds a threshold, then the WTRU Triggers an indication to the network.

To avoid reference symbol collisions due to PCI confusion, the schedule and periodicity of transmitting reference symbols can be centrally managed at the macro / network level or negotiated between neighbors. The WTRU may be configured to send a report to the network upon detecting any reference signal in the configured window set.

A network based positioning method is described herein. Apart from location service support for a particular WTRU, the E-SMLC may interact with elements in the E-UTRAN to obtain measurement information to assist in assisting one or more location methods for all WTRUs. In one alternative, the WTRU may be configured to autonomously initiate transmission of the required positioning reference signal for uplink based WTRU positioning measurement, so that the eNB can estimate its location. This may be initiated by the WTRU based on the fingerprinting information.

The measurement configuration may include an additional configuration threshold that sets a rule when the WTRU may initiate transmission of the location reference signal.

2A illustrates an example method. At 200, the WTRU receives area offload information. At 202, the WTRU makes a coverage area determination that the WTRU may be within the coverage area of the small cell. At 204, the WTRU sends an offload indication to the network. In connected mode, the WTRU may send an offload indication over the established connection, while in idle mode, the WTRU may first initiate an RRC connection prior to sending the offload indication. 2B illustrates an alternative exemplary method. At 206, the WTRU receives area offload information from the network. At 208, the WTRU makes a coverage area determination that the WTRU may be within the coverage area of the small cell. At 210, the WTRU initiates an inter-frequency and / or inter-RAT measurement. 2C illustrates another alternative exemplary method. At 212, the WTRU receives area offload information. At 214, the WTRU makes a coverage area determination that the WTRU may be within the coverage area of the small cell. At 216, the WTRU sends an offload indication to the network. At 218, the WTRU receives an inter-frequency or inter-RAT configuration message. At 220, the WTRU initiates a measurement according to the received configuration.

In one embodiment, a method includes receiving offload area information at a wireless transmit / receive unit (WTRU) from a network, making coverage area determination of a WTRU for a coverage area of a small cell based on the offload area information, and offloading Sending an indication to the network.

In an embodiment, the method comprises (i) an area defined by a center point and a radius, (ii) a set of GPS coordinates, (iii) an area defined by a plurality of GPS coordinates, and (iv) a coverage area of at least one macro cell. And (v) a list of location reference symbols, (vi) one or more PCI, (vii) one or more cell identities, (viii) the frequency at which the small cell operates, or (ix) a radio of the small cell. And offload region information including any one or more of the access technologies.

In an embodiment, the method may include offload region information received via a radio resource control (RRC) message, via a system information block, or via dedicated signaling.

In an embodiment, the method comprises at least one of the following events: cell reselection, handover to cell, expiration of a timer associated with cell reselection / handover to cell, explicit request by network, expiration of periodic timer And receiving offload area information by the WTRU based on.

In an embodiment, the method may include coverage area determination made by comparing the WTRU location with a reference location and radius or by comparing the WTRU location with a plurality of location reference points.

In an embodiment, the method may use an offload indication that includes one of a WTRU location, a small cell ID, a small cell frequency, or an index value of a stored location.

In an embodiment, the method may further include receiving the small cell configuration from the base station in response to the offload indication.

In an embodiment, the method may include the small cell configuration being an inter-frequency, inter-RAT or intra-frequency measurement configuration.

In an embodiment, the method may include indicating that an offload indication is entering the small cell coverage area or that the WTRU has left the small cell coverage area.

In an embodiment, the method may include sending the offload indication to the network subject to a low mobility state of the WTRU.

In an embodiment, the method may include that the low mobility state is determined for global positioning system (GPS) information.

In an embodiment, the method may include sending the offload indication to the macro cell subject to the traffic level of the WTRU.

In an embodiment, the method may include the offload indication message including an RRC message.

In an embodiment, the method may include that the RRC message is a modified proximity indication message that includes an information element belonging to an offload.

In an embodiment, the method may include that the RRC message is an RRC measurement report message modified to include an information element indicating offloading.

In an embodiment, the method may include the following information elements: an offload indication message, an indication that the WTRU enters the offload area, an indication that the WTRU leaves the offload area, an identifier of the offload area where the WTRU may be offloaded, the WTRU Can be offloaded, the cell ID of the potential target cell where the WTRU can be offloaded, the PCI of the potential target cell where the WTRU can be offloaded, the radio access technology that the WTRU can be offloaded, It may include including at least one of the areas located.

In an embodiment, the method may include the following events: cell reselection, handover to cell, expiration of a timer associated with cell reselection / handover to cell, explicit request by network, expiration of periodic timer, WTRU for which Verifying valid offload region information at the WTRU when at least one of the expiration of the timer started at the last time of verifying whether the offload region information is lacking may occur.

In an embodiment, the method provides that the WTRU is configured to perform the following triggers: the validity timer expires for some offload area information, the WTRU moves out of the cell (eg, due to cell reselection or handover). ), The WTRU moves to idle mode, the WTRU performs an inter-frequency or inter-RAT handover, the WTRU moves outside the home network, the WTRU changes the public network, the WTRU turns off Delete stored offload region information based on any one of those explicitly mentioned by the network to delete the load region information, the WTRU changing the RRC state, or the WTRU obtaining new offload region information. It may include doing.

In an embodiment, one method comprises receiving offload region information at a wireless transmit / receive unit (WTRU) from a macro cell base station, making a determination based on offload region information that the WTRU is in a coverage area of the small cell, and Initiating an inter-frequency and / or inter-RAT measurement to detect.

In an embodiment, the method further comprises: (i) the area defined by the center point and the radius, (ii) the set of GPS coordinates, (iii) the area defined by the plurality of GPS coordinates, and (iv) at least one Coverage area of a macro cell and identity of at least one macro cell, (v) a list of location reference symbols, (vi) one or more PCI, (vii) one or more cell identities, (viii) the frequency at which the small cell operates, or (ix ) Including offload area information including any one or more of the small cell radio access technologies.

In an embodiment, the method may include receiving offload region information via a system information block.

In an embodiment, the method may include that coverage area determination is made by comparing the WTRU location to a reference location and radius, or by comparing the WTRU location with a plurality of location reference points.

In an embodiment, the method may include initiating inter-frequency and / or inter-RAT measurements subject to the low mobility state of the WTRU.

In an embodiment, the method may include initiating inter-frequency and / or inter-RAT measurements subject to the traffic level of the WTRU.

In an embodiment, the method may include the following events: cell reselection, handover to cell, expiration of a timer associated with cell reselection / handover to cell, explicit request by network, expiration of periodic timer, WTRU for which Verifying valid offload region information at the WTRU when at least one of the expiration of the timer started at the last time of verifying whether the offload region information is lacking may occur.

In an embodiment, the method includes receiving offload area information at a wireless transmit / receive unit (WTRU) from a base station, making a determination based on offload area information that the WTRU is in a coverage area of a small cell, and offloading to a network entity. Sending an indication, receiving an inter-frequency or inter-RAT measurement configuration, and initiating an inter-frequency and / or inter-RAT measurement depending on the configuration.

In an embodiment, the method further comprises: (i) the area defined by the center point and the radius, (ii) the set of GPS coordinates, (iii) the area defined by the plurality of GPS coordinates, and (iv) at least one Coverage area of a macro cell and identity of at least one macro cell, (v) a list of location reference symbols, (vi) one or more PCI, (vii) one or more cell identities, (viii) the frequency at which the small cell operates, or (ix ) Any one or more of the small cell radio access technologies.

In an embodiment, the method may include receiving offload region information via a system information block.

In an embodiment, the method may include that the coverage area determination is made by comparing the WTRU location with a reference location and radius or by comparing the WTRU location with a plurality of location reference points.

In an embodiment, the embodiment is configured to receive offload area information from a macro cell base station, make a coverage area determination of the WTRU for the coverage area of the small cell based on the offload area information, and send an offload indication to the macro cell. It may include an apparatus including a configured wireless transmit / receive unit (WTRU).

In an embodiment, the apparatus may include a WTRU configured to make coverage area determination by comparing the WTRU location with a reference location and radius or by comparing the WTRU location with a plurality of location reference points.

In an embodiment, the apparatus may be further configured to receive the small cell configuration from the base station in response to the offload indication.

In an embodiment, the apparatus is further configured to send an offload indication to the macro cell based on the low mobility state of the WTRU.

In an embodiment, the apparatus is further configured to send an offload indication to the macro cell based on the traffic level of the WTRU.

In an embodiment, the device may be configured with the following events: cell reselection, handover to cell, expiration of a timer associated with cell reselection / handover to cell, explicit request by network, expiration of periodic timer, WTRU for which And is configured to verify valid offload region information when at least one of the expiration of a timer started at the last time of verifying whether the offload region information is lacking occurs.

In an embodiment, the apparatus may include the following triggers, that is, the validity timer expires for some offload area information, the WTRU moves out of the cell (eg, due to cell reselection or due to handover). ), The WTRU moves to idle mode, the WTRU performs an inter-frequency or inter-RAT handover, the WTRU moves outside the home network, the WTRU changes the public network, the WTRU offload area Further delete the stored offload area information based on any one of those explicitly mentioned by the network to delete the information, the WTRU changing the RRC state, or the WTRU getting new offload area information. It is composed.

In an embodiment, the apparatus or system may be configured to perform any of the methods described herein.

In an embodiment, the base station or evolved NodeB can be configured to perform any of the methods described herein.

In an embodiment, a tangible computer readable storage medium stores thereon computer executable instructions for performing any of the above methods.

Modifications of the above described methods, apparatus and systems are possible without departing from the scope of the present invention. In view of the wide range of embodiments that can be applied, it is to be understood that the illustrated embodiments are merely examples and should not be taken as limiting the scope of the following claims. For example, the example embodiments described herein include a portable device that can include or be used with any suitable voltage source, such as a battery that provides any suitable voltage.

Although features and elements are described above in particular combinations, one of ordinary skill in the art will appreciate that each feature or element can be used alone or in any combination with other features and elements. In addition, the methods described herein may be implemented in computer programs, software or firmware incorporated into a computer readable medium for execution by a computer or a processor. Examples of computer readable media include electronic signals (transmitted over a wired or wireless connection) and computer readable storage media. Computer-readable storage media include magnetic media such as read-only memory (ROM), random access memory (RAM), registers, cache memory, semiconductor memory devices, internal hard disks, and removable disks, magnetic optical media, and CD-ROM disks; Optical media such as, but not limited to, digital versatile discs (DVDs). In association with software, the processor may be used to implement a radio frequency transceiver for use in a WTRU, UE, terminal, base station, RNC, or any host computer.

Moreover, in the embodiments described above, other devices are noted, including processing platforms, computing systems, controllers, and processors. These devices may include at least one central processing unit (“CPU”) and memory. As practiced by those skilled in the art of computer programming, reference to symbolic representations of operations and operations or instructions may be performed by various CPUs and memories. Such operations and operations or instructions may be referred to as "executed", "computer executed" or "CPU executed".

Those skilled in the art will understand that operations and symbolically represented operations or instructions include the manipulation of electrical signals by the CPU. The electrical system can cause the final conversion or reduction of the electrical signal and the retention of data bits at memory locations within the memory system, thereby not only reconfiguring or otherwise altering the operation of the CPU, but also causing other processing of the signal. Represents a data bit. The memory location in which the data bits are maintained is a physical location with specific electrical, magnetic, optical or organic characteristics that correspond to or represent the data bits. It is to be understood that the example embodiments are not limited to the platforms or CPUs described above, but other platforms and CPUs may support the described methods.

The data bits may also be read by a CPU, magnetic disks, optical disks, and any other volatile (eg, random access memory ("RAM")) or non-volatile (eg, read-only memory ("ROM")]. And may be maintained on a computer readable medium including a mass storage system. Computer-readable media can include cooperative or interconnected computer-readable media distributed among a number of interconnected processing systems that can be exclusively on a processing system or can be local or remote to a processing system. It is to be understood that the example embodiments are not limited to the memory described above, but other platforms and memories may support the described methods.

No elements, acts, or instructions used in the description of the present application should be construed as critical or essential to the present invention unless so explicitly described. Also, as used herein, each singular expression is intended to include one or more items. The term "single" or similar language is used where only one item is intended. In addition, "any of" preceding a list of a plurality of items and / or a category of a plurality of items may be an item and / or a category of items "individually or in conjunction with other items and / or other categories of items. Any of "," any combination of, "" any number of, "and / or" any combination of any of ". Also, as used herein, the term "set" is intended to include any number of items including zeros. Also, as used herein, the term "number" is intended to include any number including zero.

Moreover, the claims should not be read as limited to the described order or elements unless stated to that effect. Moreover, the use of the term “means” in any claim does not apply to 35 U.S.C. Any claim that is intended to invoke § 112, ¶ 6, and does not have the term "means" is not intended to be so.

100: communication system 102: wireless transmit / receive unit (WTRU)
104: radio access network (RAN) 106: core network
108: public switched telephone network (PSTN) 110: Internet
112: other network 120: transceiver
124: speaker / microphone 126: keypad
128: display / touchpad 130: non-removable memory
132: removable memory 164: serving gateway

Claims (18)

Receiving offload area information from a wireless transmit / receive unit (WTRU) from a network;
Making a coverage area determination of the WTRU for a coverage area of a small cell based on the offload region information; And
Sending offload instructions to the network
≪ / RTI > The method of claim 1, wherein the offload region information comprises (i) an area defined by a center point and a radius, (ii) a set of GPS coordinates, (iii) an area defined by a plurality of GPS coordinates, and (iv) at least one Coverage area of the macro cell and the identity of the at least one macro cell, (v) a list of Position Reference Symbols, (vi) one or more PCI, (vii) one or more cell identity, (viii) 1) any one or more of the frequency at which the small cell operates or (ix) the radio access technology of the small cell. The method of claim 1, wherein the offload region information is received via a Radio Resource Control (RRC) message. The method of claim 1, wherein the offload area information is received via a system information block. The method according to claim 1, wherein the offload area information includes the following events: cell reselection, handover to cell, expiration of a timer associated with cell reselection / handover to cell, explicit request by network, periodic timer Expiration, received by the WTRU based on the occurrence of at least one of. The method of claim 1, wherein the coverage area determination is made by comparing the WTRU location with a reference location and radius or by comparing the WTRU location with a plurality of location reference points. The method of claim 1, wherein the offload indication comprises one of a WTRU location, a small cell ID, a small cell frequency, or an index value of a stored location. 2. The method of claim 1, further comprising receiving a small cell configuration from a base station in response to the offload indication. 9. The method of claim 8, wherein the small cell configuration is an inter-frequency, inter-RAT or intra-frequency measurement configuration. The method of claim 1, wherein sending the offload indication to the network is subject to a low mobility state of the WTRU. 2. The method of claim 1, wherein sending the offload indication to a macro cell is subject to the traffic level of the WTRU. A wireless transmit / receive unit (WTRU) configured to receive offload region information from a macro cell base station, to determine a coverage area of a WTRU for a coverage area of a small cell based on the offload region information, and to send an offload indication to a macro cell. Device). The apparatus of claim 12, wherein the WTRU is configured to make the coverage area determination by comparing a WTRU location with a reference location and radius or by comparing the WTRU location with a plurality of location reference points. 13. The apparatus of claim 12, wherein the WTRU is further configured to receive a small cell configuration from the base station in response to the offload indication. 13. The apparatus of claim 12, wherein the WTRU is further configured to send the offload indication to the macro cell based on the low mobility state of the WTRU. 13. The apparatus of claim 12, wherein the WTRU is further configured to send the offload indication to the macro cell based on the traffic level of the WTRU. 13. The system of claim 12, wherein the WTRU is configured to perform the following events: cell reselection, handover to cell, expiration of a timer associated with cell reselection / handover to cell, explicit request by network, expiration of periodic timer, And verify valid offload area information when at least one of the expiration of a timer started at the last time that the WTRU verified whether there is lack of valid offload area information occurs. 13. The system of claim 12 wherein the WTRU is also capable of:
A validity timer expires for some offload region information,
The WTRU moves out of the cell (eg due to cell reselection or due to handover),
The WTRU moves to idle mode,
The WTRU performing handover between frequencies or between RATs,
WTRUs move out of the home network,
Changing the public network by the WTRU,
Explicitly mentioned by the network so that the WTRU deletes offload area information,
The WTRU changes the RRC state, or
WTRU getting new offload area information
And delete the stored offload area information based on any one of the following.

Images